U.S. patent application number 13/547191 was filed with the patent office on 2013-02-14 for image sensor for semiconductor light-sensitive device, manufacturing method thereof, image processing apparatus using the same, and method for detecting color signal.
This patent application is currently assigned to Dongbu HiTek Co., Ltd.. The applicant listed for this patent is Hoon JANG. Invention is credited to Hoon JANG.
Application Number | 20130037861 13/547191 |
Document ID | / |
Family ID | 47676979 |
Filed Date | 2013-02-14 |
United States Patent
Application |
20130037861 |
Kind Code |
A1 |
JANG; Hoon |
February 14, 2013 |
IMAGE SENSOR FOR SEMICONDUCTOR LIGHT-SENSITIVE DEVICE,
MANUFACTURING METHOD THEREOF, IMAGE PROCESSING APPARATUS USING THE
SAME, AND METHOD FOR DETECTING COLOR SIGNAL
Abstract
An image sensor for a semiconductor light-sensitive device
including a semiconductor substrate and a light receiving device
configured to receive light and generate a signal from the light.
The image sensor may include an electron collecting device formed
in the semiconductor substrate to receive at least a portion of the
electrons generated by the light in the light receiving device. The
image sensor may include a first type device isolation film
configured to isolate the light receiving device from the electron
collecting device. The image sensor may include a shielding film
formed over the semiconductor substrate and configured to shield
the first electron collecting device from the light.
Inventors: |
JANG; Hoon; (Seoul,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
JANG; Hoon |
Seoul |
|
KR |
|
|
Assignee: |
Dongbu HiTek Co., Ltd.
Seoul
KR
|
Family ID: |
47676979 |
Appl. No.: |
13/547191 |
Filed: |
July 12, 2012 |
Current U.S.
Class: |
257/222 ;
257/E27.151; 257/E31.078; 438/76 |
Current CPC
Class: |
H01L 27/1463 20130101;
H01L 27/14623 20130101; H01L 27/1461 20130101 |
Class at
Publication: |
257/222 ; 438/76;
257/E27.151; 257/E31.078 |
International
Class: |
H01L 27/148 20060101
H01L027/148; H01L 31/18 20060101 H01L031/18 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 11, 2011 |
KR |
10-2011-0080202 |
Claims
1. An apparatus comprising: a semiconductor substrate; a light
receiving device formed in the semiconductor substrate, wherein the
light receiving device is configured to receive light and generate
electrons in response to the received light; at least one electron
collecting device formed in the semiconductor substrate, wherein
said at least one electron collecting device is configured to
receive at least a portion of the electrons generated by the light
receiving device; a first type device isolation film configured to
isolate the light receiving device from said at least one electron
collecting device; and a shielding film formed over the
semiconductor substrate, wherein the shielding film is configured
to shield said at least one electron collecting device from
light.
2. The apparatus of claim 1, wherein the apparatus is an image
sensor for a semiconductor light-sensitive device.
3. The apparatus of claim 1, wherein the light receiving device has
a width that is greater than said at least one electron collecting
device.
4. The apparatus of claim 1, comprising at least one electron
movement guide layer formed in the semiconductor substrate, wherein
said at least one electron movement guide layer is configured to
guide electrons generated in the light receiving device to said at
least one electron collecting device.
5. The apparatus of claim 4, wherein said at least one electron
movement guide layer is formed under the first type isolation
film.
6. The apparatus of claim 1, wherein said at least one electron
collecting device comprises: a first electron collecting device
isolated from the light receiving device by the first type device
isolation film; and a second electron collecting device isolated
from the first electron collecting device.
7. The apparatus of claim 6, wherein: the first electron collecting
device is adjacent to the second electron collecting device; and
the apparatus comprises a second type device isolation film,
wherein the second type device isolation film is configured to
isolate the first electron collecting device and second electron
collecting device.
8. The apparatus of claim 6, wherein the first type device
isolation film has a width greater than the second type device
isolation film.
9. The apparatus of claim 6, wherein: said at least one electron
movement guide layer comprises a first electron movement guide
layer formed in the semiconductor substrate, formed under the first
type device isolation film, and formed substantially between the
light receiving device and the first electron collecting device at
a specific light receiving depth of the light receiving device; and
a second electron movement guide layer formed in the semiconductor
substrate, formed under the first type device isolation film,
formed under the second type device isolation film, and formed
substantially between the light receiving device and the second
electron collecting device at a specific light receiving depth of
the light receiving device.
10. The apparatus of claim 9, wherein: the width of the second
electron movement guide layer is greater than the first electron
movement guide layer; the second electron movement guide layer is
formed under the first electron movement guide layer
11. A method comprising: forming a first type device isolation film
in a semiconductor substrate, wherein the first type device
isolation film defines an active region of the semiconductor
substrate; forming a light receiving device in the semiconductor
substrate, wherein the light receiving device is configured to
receive light within the semiconductor substrate; forming an
electron collecting device in the semiconductor substrate, wherein
the electron collecting device is configured to receive at least a
portion of the electrons generated by the light receiving device,
wherein the electron collecting device and the light receiving
device are isolated by the first type isolation film; and forming a
shielding film over the semiconductor substrate, wherein the
shielding film is configured to shield the electron collecting
device from light.
12. The method of claim 11, wherein the method is a method of
manufacturing an image sensor in a semiconductor light-sensitive
device in a semiconductor substrate.
13. The method of claim 11, wherein the light receiving device has
a greater width than the electron collecting device.
14. The method of claim 11, comprising forming an electron movement
guide layer in the semiconductor substrate between the light
receiving device and the electron collecting device.
15. The method of claim 11, wherein: the electron collecting device
comprises a first electron collecting device isolated from the
light receiving device by the first type device isolation film; the
electron collecting device comprises a second electron collecting
device isolated from the first electron collecting device; wherein
the first type device isolation film is formed together with a
second type device isolation film; and the second type device
isolation film is configured to isolate the adjacent first electron
collecting device and second electron collecting device from each
other.
16. The method of claim 15, wherein the first type device isolation
film has width greater than the second type device isolation
film.
17. The method of claim 15, comprising: forming a first electron
movement guide layer in the semiconductor substrate at a specific
light receiving depth of the light receiving device substantially
between the light receiving device and the first electron
collecting device; and forming a second electron movement guide
layer in the semiconductor substrate at a specific light receiving
depth of the light receiving device substantially between the light
receiving device and the the second electron collecting device.
18. An apparatus comprises: a semiconductor substrate; a light
receiving device formed in the semiconductor substrate and
configured to receive light; an electron collecting device formed
in the semiconductor substrate and configured to receive at least a
portion of electrons generated by light received by the light
receiving device; a first type device isolation film formed in the
semiconductor substrate and configured to isolate the light
receiving device from the electron collecting device; and a
shielding film formed over the semiconductor substrate and
configured to shield the electron collecting device from light,
wherein the signal processor detects a color signal included in the
light based on a ratio between optical current flowing through the
light receiving device and optical current flowing through the
electron collecting device.
19. The apparatus of claim 18, wherein: the apparatus is an image
processing apparatus using an image sensor in a semiconductor
light-sensitive device; and the image processing apparatus
comprises an image sensor and a signal processor.
20. The image processing apparatus of claim 18, wherein: the
electron collecting device comprises a first electron collecting
device isolated from the light receiving device by the first type
device isolation film and a second electron collecting device
configured to be isolated from the first electron collecting
device, wherein the image sensor further comprises a second type
device isolation film configured to isolate the adjacent first
electron collecting device and second electron collecting device
from each other; the image processing apparatus comprises a first
electron movement guide layer formed in the semiconductor substrate
at a specific light receiving depth of the light receiving device
substantially between the light receiving device and the first
electron collecting device; and the image processing apparatus
comprises a second electron movement guide layer formed in the
semiconductor substrate at a depth that is greater than the
specific light receiving depth of the semiconductor substrate
substantially between the light receiving device and the second
electron collecting device; and the signal processor detects a
color signal included in the light based on a ratio among optical
current flowing through the light receiving device, optical current
flowing to the first electron collecting device through the first
electron movement guide layer, and optical current flowing to the
second electron collecting device through the second electron
movement guide layer.
Description
[0001] The present application claims priority to Korean Patent
Application No. 10-2011-0080202 (filed on Aug. 11, 2011), which is
hereby incorporated by reference in its entirety.
BACKGROUND
[0002] Light produced from an object existing in nature may have
characteristic values in wavelength or similar unit. An image
sensor is an apparatus that may pick up an image of an object by
using the properties of a semiconductor device responsive to
external energy. A pixel of an image sensor may detect light
produced from an object and may convert it into an electrical
value.
[0003] Such an image sensor may be classified into a charge coupled
device (CCD) based on silicon semiconductor and a complementary
metal oxide semiconductor (CMOS) image sensor fabricated by a
submicron CMOS fabrication technology.
[0004] Of these image sensors, the CCD is a device in which charge
carriers may be stored in a capacitor and transferred such that
each MOS capacitor is closely disposed to each other. However, the
CCD has various disadvantages, such as relatively complicated drive
mode, relatively higher power consumption, impracticability of
integrating a signal processing circuit in a chip for the CCD due
to many mask processes and other reasons. In order to overcome
these disadvantages, many studies may have been done towards
development of the CMOS image sensor.
[0005] The CMOS image sensor may obtain an image by forming a
photodiode (PD) and a MOS transistor within a unit pixel to detect
signals in a switching mode. The CMOS image sensor may have the
advantages of relatively low manufacturing costs, relatively low
power consumption, and relatively easy integration into a
peripheral circuit chip in comparison with a CCD. Since a CMOS
image sensor may be produced using a CMOS fabrication technology,
the CMOS image sensor may be easily integrated into a peripheral
system for performing operations such as amplification and signal
processing, resulting in minimized manufacturing costs. A CMOS
image sensor may have a relatively rapid processing speed and a
relatively low power consumption which corresponds to approximately
1% of the power consumption of the CCD.
[0006] Meanwhile, because a unit pixel of the CMOS image sensor may
realize only one color, filters may be used for each pixel to
filter only light of a desired wavelength from white light, and
then red, green, and blue (RGB) values for each pixel may be
calculated and restored by interpolation or similar. A color filter
array for each unit pixel may be formed to realize red, green, and
blue colors.
[0007] However, image sensors that may realize a fine line width
circuit may be accomplished along with the development of
semiconductor processing techniques. As the overall chip size, as
well as the size of a unit pixel, gets progressively smaller with
development, the size of each color filter is also minimized.
[0008] A material for producing a color filter array may be a
polymer-based material, which may be very difficult to handle in an
actual process and has a relatively high likelihood to undesirably
maximize the rate of defects of manufactured devices. The
polymer-based material of the color filter array may play a major
role in minimizing the overall chip performance because it also
serves to block the majority of light entering each unit pixel.
This is because a color filter is supposed to selectively pass only
light in a specific wavelength range, but may be unable to
completely filter the light due to the characteristics of the color
filter.
[0009] Therefore, there may be rise in demand for a method for
realizing a color without the use of color filters.
[0010] FIG. 1 is a cross-sectional view of a color image sensor
from which color filters are removed, according to the related art.
Referring to FIG. 1, the image sensor according to the related art
may include at least one of: (1) A substrate SUB which may be
etched at a First thickness d1 in a first unit pixel region `a` for
realizing a color (e.g. R or magenta) of a first wavelength, etched
at a second thickness d2 which may be relatively greater than the
first thickness d1 in a second unit pixel region `b` for realizing
a color (e.g. G or yellow) of a second wavelength relatively
shorter than the first wavelength, and etched at a third thickness
d3 which may be relatively greater than the second thickness d2 in
a third unit pixel region `c` for realizing a color (e.g. B or
cyan) of a third wavelength relatively shorter than the second
wavelength. (2) first photodiode PD1 formed at a first depth d1
from the substrate SUB etched in the first unit pixel region `a`.
(3) A second photodiode PD2 formed at a second depth d2' which may
be relatively greater than the first depth d1' from the substrate
SUB etched in the second unit pixel region `b`. (4) A third
photodiode PD3 formed at a third depth d3' which may be relatively
greater than the second depth d2' from the substrate SUB etched in
the third unit pixel region `c.` Here, `X` may indicate the
position of the substrate SUB before etching.
[0011] The distance from the rear surface of the substrate SUB to
each of the bottoms of the first photodiode PD1, the second
photodiode PD2, and the third photodiode PD3 may be substantially
equal. In other words, the sum of the first thickness d1 and the
first depth d1', the sum of the second thickness d1 and the second
depth d2', and the sum of the third thickness d3 and the third
depth d3' may be substantially equal to each other.
[0012] The substrate SUB may be composed of a first conductive,
such as P-type, relatively highly doped region P++ and a first
conductive epi-grown region P-epi.
[0013] The first to third photodiodes PD1 to PD3 may each include a
first impurity region P0 of the first conductive type extending
from the surface of the substrate SUB to the bottom of the
substrate SUB in each of the a, b, and c regions, and a second
impurity region (n- region) of the second conductive type, such as
N-type, adjoining the first impurity region P0 and extending from
the first impurity region P0 to each of the formation depths d1',
d2', and d3' of the photodiodes PD1 to PD3.
[0014] A microlens ML may be formed on the top, overlapped with the
photodiodes PD1 to PD3. According to the related art having the
above-mentioned configuration, each color may be realized in the
first to third unit pixel regions a, b, and c without respective
color filters.
[0015] RGB, which may have three primary colors of light, may have
different wavelengths. R may have a wavelength of about 0.55 .mu.m
to 0.6 .mu.m, G may have a wavelength of about 0.45 .mu.m to 0.55
.mu.m, and B may have a wavelength of about 0.35 .mu.m to 0.45
.mu.m. Due to the relative differences in wavelength, the B color
having a relatively short wavelength may have less depth of
transmission through the silicon substrate SUB than the G color,
and the G color may have less depth of transmission through the
silicon substrate SUB than the R color.
[0016] Thus, the depth at which each color enters the substrate SUB
and forms an electron hole pair may vary. By taking the depth of
transmission varying with the wavelength differences between lights
of respective colors into consideration, the n- region of the
photodiode PD3 is made shallow in the unit pixel region c for
realizing the B color having a short wavelength, the n- region of
the photodiode PD2 is made deeper than `c` in the unit pixel region
b for realizing the G color having a longer wavelength than the B
color, and the n- region of the photodiode PD1 is made deeper than
`b` in the unit pixel region a for realizing the R color having a
longer wavelength than the G color.
[0017] White light is a mixture of all the wavelengths of light.
The light of each wavelength may have different penetration depth.
That is, light passes through the silicon substrate SUB and the
wavelengths of RGB penetrate to different depths. The difference in
penetration depth may be an optical characteristic, and therefore
the penetration depth may not be adjusted as desired. As the
wavelengths may penetrate to the penetration depth d1' from the
white light that has reached the surface of the substrate SUB of
`a`, the wavelengths of the colors excluding the R color may be all
extinguished and only the light having the wavelength of the R
color may enter the first photodiode PD1 to generate
photoelectrons.
[0018] As the wavelengths may penetrate to the penetration depth
d3' from the white light that may have reached the surface of the
substrate SUB of `c`, R and G pass through the silicon substrate
SUB and may be all extinguished, and only the light having the
wavelength of the B color may enter the third photodiode PD3 to
generate photoelectrons. The same applies to `b`.
[0019] According to the related art, colors may be realized without
the use of color filters. In case of a product using a linear
sensor, however, pixels may not be disposed like a general image
sensor because they may have to be disposed transversely due to the
characteristics of the linear sensor, and thus red, green, and blue
may be disposed separately. Consequently, the longitudinal width of
a chip may need to be maximized, thus relatively enlarging the
overall chip size.
SUMMARY
[0020] In view of the above, the embodiments provide an image
sensor for a semiconductor light-sensitive device, which may
realize colors without the use of color filters only by including
at least two optical devices (e.g. a light receiving device and an
electron collecting device) because the image sensor may be
designed and fabricated in such a manner as to include at least one
electron collecting device permitting part of the electrons
generated by light in the light receiving device to move thereto
without directly receiving light, and a method for fabricating
substantially the same.
[0021] Embodiments may provide an image processing apparatus
including an image sensor and a method for detecting a color signal
using substantially the same. In accordance with embodiments, there
may be provided an image sensor for a semiconductor light-sensitive
device, the image sensor including at least one of: (1) A
semiconductor substrate. (2) A light receiving device which may be
configured to be formed within the semiconductor substrate to
receive light. (3) An electron collecting device which may be
configured to be formed within the semiconductor substrate to
permit part of the electrons generated by the light in the light
receiving device to move thereto. (4) A first type device isolation
film which may be configured to isolate the light receiving device
from the electron collecting device. (5) A shielding film which may
be configured to be formed on and/or over top of the semiconductor
substrate to shield the first electron collecting device from the
light.
[0022] In embodiments, the light receiving device may have a
relatively greater width than the electron collecting device. The
image sensor may further comprise an electron movement guide layer
configured to be formed between the light receiving device and the
electron collecting device which may be formed within the
semiconductor substrate, in accordance with embodiments.
[0023] In embodiments, the electron collecting device may include
at least one of: (1) A first electron collecting device configured
to be isolated from the light receiving device by the first type
device isolation film. (2) A second electron collecting device may
be configured to be isolated from the first electron collecting
device, wherein the image sensor may further include (in
embodiments) a second type device isolation film configured to
isolate the adjacent first electron collecting device and second
electron collecting device from each other.
[0024] The first type device isolation film may have a relatively
greater width than the second type device isolation film, in
accordance with embodiments. The image sensor may include at least
one of: (1) A first electron movement guide layer configured to be
formed in the area extending from the position of the light
receiving device to the position of the first electron collecting
device at a specific light receiving depth of the light receiving
device. (2) A second electron movement guide layer which may be
configured to be formed in the area extending from the position of
the light receiving device to the position of the second electron
collecting device at a light receiving depth relatively greater
than the specific light receiving depth.
[0025] In accordance with embodiments, a method for manufacturing
an image sensor for a semiconductor light-sensitive device may
include at least one of: (1) Forming a first type device isolation
film which may be configured to define an active region within a
semiconductor substrate. (2) Forming a light receiving device which
may be configured to receive light within the semiconductor
substrate and an electron collecting device may be configured to
permit part of the electrons generated by the light to move thereto
to be isolated by the first type isolation film. (3) Forming a
shielding film on top of the semiconductor substrate to shield the
electron collecting device from the light.
[0026] In embodiments, the light receiving device may be formed to
have a relatively greater width than the electron collecting
device. The method may further include forming an electron movement
guide layer between the light receiving device and the electron
collecting device which are formed within the semiconductor
substrate. The electron collecting device may he formed to include
a first electron collecting device isolated from the light
receiving device by the first type device isolation film and a
second electron collecting device may be isolated from the first
electron collecting device, and the first type device isolation
film may be formed together with a second type device isolation
film configured to isolate the adjacent first electron collecting
device and second electron collecting device from each other, in
accordance with embodiments.
[0027] In embodiments, the first type device isolation film may be
formed to have a greater width than the second type device
isolation film. The method may further include at least one of: (1)
Forming a first electron movement guide layer in the area extending
from the position of the light receiving device to the position of
the first electron collecting device at a specific light receiving
depth of the light receiving device. (2) Forming a second electron
movement guide layer in the area extending from the position of the
light receiving device to the position of the second electron
collecting device at a light receiving depth relatively greater
than the specific light receiving depth.
[0028] In accordance with embodiments, there may be provided an
image processing apparatus using an image sensor for a
semiconductor light-sensitive device, wherein the image processing
apparatus may include an image sensor for a semiconductor
light-sensitive device and a signal processor, wherein the image
sensor may include at least one of: (1) A semiconductor substrate.
(2) A light receiving device which may be configured to be formed
within the semiconductor substrate to receive light. (3) Electron
collecting device which may be configured to be formed within the
semiconductor substrate to permit part of the electrons generated
by the light in the light receiving device to move thereto. (4) A
first type device isolation film which may be configured to isolate
the light receiving device from the electron collecting device. (5)
A shielding film which may be configured to be formed on and/or
over top of the semiconductor substrate to shield the electron
collecting device from the light, wherein the signal processor may
detect a color signal included in the light based on a ratio
between optical current flowing through the light receiving device
and optical current flowing through the electron collecting
device.
[0029] The electron collecting device may include at least one of:
(1) A first electron collecting device isolated from the light
receiving device by the first type device isolation film. (2) A
second electron collecting device which may be configured to be
isolated from the first electron collecting device, wherein the
image sensor may further include a second type device isolation
film configured to isolate the adjacent first electron collecting
device and second electron collecting device from each other. (3) A
first electron movement guide layer which may be configured to be
formed in the area extending from the position of the light
receiving device to the position of the first electron collecting
device at a specific light receiving depth of the light receiving
device. (4) A second electron movement guide layer configured to be
formed in the area extending from the position of the light
receiving device to the position of the second electron collecting
device at a light receiving depth relatively greater than the
specific light receiving depth, and wherein the signal processor
may detect a color signal included in the light based on a ratio
among optical current flowing through the light receiving device,
optical current flowing to the first electron collecting device
through the first electron movement guide layer, and, optical
current flowing to the second electron collecting device through
the second electron movement guide layer.
[0030] In accordance with embodiments, there may be provided a
method for detecting a color signal by an image processing
apparatus including an image sensor for a semiconductor
light-sensitive device, wherein the image sensor may include at
least one of: (1) A semiconductor substrate. (2) A light receiving
device which may be configured to be formed within the
semiconductor substrate to receive light. (3) Electron collecting
device which may be configured to be formed within the
semiconductor substrate to permit part of the electrons generated
by the light in the light receiving device to move thereto. (4) A
first type device isolation film which may be configured to isolate
the light receiving device from the electron collecting device. (5)
A shielding film configured to be formed on and/or over the top of
the semiconductor substrate to shield the electron collecting
device from the light, wherein the method for detecting a color
signal may detect a color signal included in the light based on a
ratio between optical current flowing through the light receiving
device and optical current flowing through the electron collecting
device.
[0031] The electron collecting device may include at least one of:
(1) A first electron collecting device isolated from the light
receiving device by the first type device isolation film. (2) A
second electron collecting device configured to be isolated from
the first electron collecting device, wherein the image sensor may
further include (in embodiments) a second type device isolation
film configured to isolate the adjacent first electron collecting
device and second electron collecting device from each other. (3) A
first electron movement guide layer configured to be formed in the
area extending from the position of the light receiving device to
the position of the first electron collecting device at a specific
light receiving depth of the light receiving device. (4) A second
electron movement guide layer which may be configured to be formed
in the area extending from the position of the light receiving
device to the position of the second electron collecting device at
a light receiving depth which may be relatively greater than the
specific light receiving depth, wherein the method for detecting a
color signal may detect the color signal included in the light
based on a ratio among optical current flowing through the light
receiving device, optical current flowing to the first electron
collecting device through the first electron movement guide layer,
and optical current flowing to the second electron collecting
device through the second electron movement guide layer.
[0032] In accordance with the embodiments, colors may be realized
without the use of color filters, and therefore the process yield
may be maximized, thereby minimizing the cost and relatively
improving the overall chip performance. In embodiments, colors may
be realized without the use of color filters only by including at
least two optical devices (e.g. a light receiving device and an
electron collecting device) because the image sensor may be
designed and fabricated in such a manner as to include at least one
electron collecting device permitting part of the electrons
generated by light in the light receiving device to move thereto
without directly receiving light. As a consequence, the process
yield may be further maximized, thereby minimizing the cost and
relatively improving the overall chip performance. In addition, the
overall chip size may be minimized as the longitudinal width of a
chip may be reduced in case of a product using a linear sensor.
DRAWINGS
[0033] The above and other objects and features of embodiments may
become apparent from the following description of embodiments,
given in conjunction with the accompanying drawings, in which:
[0034] Example FIG. 1 is a cross-sectional view of a color image
sensor from which color filters are removed, according to the
related art.
[0035] Example FIG. 2 is a top plan view of an image sensor for a
semiconductor light-sensitive device, in accordance with
embodiments.
[0036] Example FIG. 3 is a cross-sectional view illustrating the
structure of the image sensor for the semiconductor light-sensitive
device, in accordance with embodiments.
[0037] Example FIG. 4 is a top plane view of an image sensor for a
semiconductor light-sensitive device, in accordance with
embodiments.
[0038] Example FIG. 5 is a cross-sectional view taken along virtual
line V-V' shown in FIG. 4 to explain the structure of the image
sensor for the semiconductor light-sensitive device in accordance
with embodiments.
[0039] Example FIGS. 6A to 6C are cross-sectional views
illustrating a method for fabricating an image sensor for a
semiconductor light-sensitive device, in accordance with
embodiments.
[0040] Example FIG. 7 is a cross-sectional view illustrating the
structure of an image sensor for a semiconductor light-sensitive
device, in accordance with embodiments.
[0041] Example FIG. 8 is a cross-sectional view illustrating the
structure of an image sensor for a semiconductor light-sensitive
device, in accordance of embodiments.
[0042] Example FIGS. 9A to 9C are cross-sectional views
illustrating a method for fabricating an image sensor for a
semiconductor light-sensitive device, in accordance with
embodiments.
DESCRIPTION
[0043] Advantages and features of embodiments' methods of
accomplishing substantially the same may be understood more readily
by reference to the following detailed description of embodiments
and the accompanying drawings. The embodiments may, however, be
embodied in many different forms and may not be construed as being
limited to the embodiments set forth herein. Rather, these
embodiments may be provided so that this disclosure may be thorough
and complete and may fully convey the concept of the embodiments to
those skilled in the art, and the embodiments may only be defined
by the appended claims.
[0044] Example FIG. 2 is a top plan view of an image sensor for a
semiconductor light-sensitive device, in accordance with
embodiments. Example FIG. 3 is a cross-sectional view taken along
virtual line A-A' of FIG. 2 to explain the structure of the image
sensor for the semiconductor light-sensitive device, in accordance
with embodiments.
[0045] As shown in FIGS. 2 and 3, an image sensor in accordance
with embodiments may include a semiconductor substrate 110. A light
receiving device 131 may be formed within the semiconductor
substrate 110 to receive light 10. A first electron collecting
device 133a may be formed within the semiconductor substrate 110 to
permit part of the electrons generated by the light 10 in the light
receiving device 131 to move thereto. A first type device isolation
film 121 for isolating the light receiving device 131 from the
first electron collecting device 133a, and a shielding film 140 may
be formed on and/or over the top of the semiconductor substrate 110
to shield the first electron collecting device 133a from the light
10.
[0046] In the image sensor for the semiconductor light-sensitive
device, the light receiving device 131 may directly receive the
light 10. However, the first electron collecting device 133a may
not directly receive the light 10 because it may be shielded from
the light 10 by the shielding film 140, and instead may permit part
of the electrons generated by the light 10 in the light receiving
device 131 to move thereto. Therefore, the image sensor may be
designed and fabricated in such a manner that the width of the
light receiving device 131 may he relatively greater than the width
of the first electron receiving device 133a in order to maximize
the light-sensing efficiency even while minimizing the size of a
unit pixel.
[0047] In the thus-configured image sensor for the semiconductor
light-sensitive device in accordance with embodiments, when the
light receiving device 131 receives the light 10, optical current
I.sub.0 may flow in the light receiving device 131, and part of the
electrons generated by the light receiving device 131 may move to
the first electron collecting device 133a to cause optical current
I.sub.1 to flow through the first electron collecting device
133a.
[0048] RGB, which are the three primary colors of light, have
different wavelengths. R has a wavelength of about 0.55 .mu.m to
0.6 .mu.m, G has a wavelength of about 0.45 .mu.m to 0.55 .mu.m,
and B has a wavelength of about 0.35 .mu.m to 0.45 .mu.m. Due to
the relative differences in wavelength, the B color having a short
wavelength may have a relatively less depth of transmission through
the semiconductor substrate 110 than the G color, and the G color
may have a relatively less depth of transmission through the
semiconductor substrate 110 than the R color. Thus, the depth at
which each color enters the semiconductor substrate 110 and forms
an electron hole pair may vary. Moreover, the greater the depth of
transmission through the semiconductor substrate 110, the more the
number of the electrons overflowing the first type device isolation
film 121 and moving to the first electron collecting device 133a.
As a result, the optical current I.sub.1 flowing through the first
electron collecting device 133a may maximize. That is, the ratio
between the optical current I.sub.0 flowing through the light
receiving device 131 and the optical current I.sub.1 flowing
through the first electron collecting device 133a may vary with
each wavelength of the light 10.
[0049] In embodiments, if a resultant value is set in a signal
processor in advance, the resultant value being obtained by
measuring the ratio between the optical current I.sub.0 flowing
through the light receiving device 131 and the optical current
flowing through the first electron collecting device 133a for each
wavelength of the light 10, the signal processor may determine the
wavelength of the light 10 based on the ratio between the optical
current I.sub.0 flowing through the light receiving device 131 and
the optical current I.sub.1 flowing through the first electron
collecting device 133a, and may detect a color signal corresponding
to the determined wavelength.
[0050] FIG. 4 is a top plane view of an image sensor for a
semiconductor light-sensitive device in accordance with
embodiments. FIG. 5 is a cross-sectional view taken along virtual
line V-V' shown in FIG. 4 to explain the structure of the image
sensor for the semiconductor light-sensitive device in accordance
with embodiments.
[0051] In comparison with the above-described image sensor in
accordance with embodiments, the image sensor in accordance with
embodiments illustrated in FIGS. 4 and 5 may further include a
second electron collecting device 133b formed at a predetermined
depth in an upper portion of the semiconductor substrate 110 so as
to be electrically isolated from the first electron collecting
device 133a, and a second type device isolation film 123 for
isolating the adjacent first electron collecting device 133a and
second electron collecting device 133b from each other. It may be
formed such that the width of the second type device isolation film
123 may be relatively smaller than the width of the first type
device isolation film 121. This may be to prevent the distance
between the light receiving device 131 and the second electron
collecting device 133b from being unnecessarily maximized so that
the electrons generated in the light receiving device 131 may be
properly move to the second electron collecting device 133b, in
accordance with embodiments.
[0052] Embodiments may further include the second electron
collecting device 133b and the second type device isolation film
123. If a resultant value is set in a signal processor in advance,
the resultant value being obtained by measuring the ratio among the
optical current I.sub.0 flowing through the light receiving device
131, the optical current l.sub.1 flowing through the first electron
collecting device 133a, and the optical current I.sub.2 flowing
through the second electron collecting device 133b for each
wavelength of the light 10, in accordance with embodiments. In
embodiments, the signal processor may determine the wavelength of
the light 10 based on the ratio among the optical current I.sub.0
flowing through the light receiving device 131, the optical current
I.sub.1 flowing through the first electron collecting device 133a,
and the optical current I.sub.2 flowing through the second electron
collecting device 133b, and may detect a color signal corresponding
to the determined wavelength.
[0053] In comparison with the embodiments which may not include the
second electron collecting device 133b but only the first electron
collecting device 133a, embodiments may more accurately measure the
wavelength of the light 10 received by the light receiving device
131. This is because the number of comparison factors for
determining wavelength may be maximized from two optical current
values I.sub.0 and I.sub.1 to three optical current values I.sub.0,
I.sub.1, and I.sub.2.
[0054] FIGS. 6A to 6C are cross-sectional views illustrating a
method for fabricating an image sensor for a semiconductor
light-sensitive device in accordance with embodiments. Referring to
FIGS. 6a to 6c, the method for fabricating an image sensor for a
semiconductor light-sensitive device may include the second
electron collecting device 133b and the second type device
isolation film 123, in accordance with embodiments.
[0055] Referring to FIG. 6A, a first type device isolation film 121
and a second type device isolation film 123, which may define
active regions, may be formed within the semiconductor substrate
110. In embodiments, the width of the second type device isolation
film 123 may be relatively smaller than the width of the first type
device isolation film 121. This may be to prevent the distance
between the light receiving device 131 and the second electron
collecting device 133b, which may be formed later, from being
unnecessarily maximized so that the electrons generated in the
light receiving device 131 may properly move to the second electron
collecting device 133b.
[0056] Referring to FIG. 6B, the light receiving device 131 may be
formed within the semiconductor substrate 110 to receive light, the
first electron collecting device 133a to which part of the
electrons may be generated by light move may be formed to be
isolated by the first type device isolation film 121, and the
second electron collecting device 133b to which part of the
electrons may move from the light receiving device 131 may be
formed to be isolated by the second type device isolation film 123,
in accordance with embodiments. In embodiments, the light receiving
device 131, the first electron collecting device 133a, and the
second electron collecting device 133b may be simultaneously
formed, and the formation order may be interchangeable even if they
may be sequentially formed.
[0057] Referring to FIG. 6C, the shielding film 140 may be formed
on and/or over the top of the semiconductor substrate 110 to shield
the first type device isolation film 121, the first electron
collecting device 133a, the second type device isolation film 123,
and the second electron collecting device 133b from external light,
in accordance with embodiments. In embodiments, the shielding film
140 may be formed of a non-transmissive metal. In embodiments,
although the light receiving device 131 may directly receive light,
the first electron collecting device 133a and the second electron
collecting device 133b may not directly receive external light
because they may be shielded from the external light by the
shielding film 140, but part of the electrons generated in the
light receiving device may be moved by the external light.
Therefore, in order to maximize the light sensing efficiency even
while minimizing the size of a unit pixel, the image sensor may be
designed and fabricated so that the width of the light receiving
device 131 may be relatively greater than that of the first
electron collecting device 133a and the second electron collecting
device 133b.
[0058] FIG. 7 is a cross-sectional view illustrating the structure
of an image sensor for a semiconductor light-sensitive device in
accordance with embodiments. As shown in FIG. 7, the image sensor
in accordance with embodiments may include a semiconductor
substrate 210. A light receiving device 231 may be formed within
the semiconductor substrate 210 to receive external light. A first
electron collecting device 233a may be formed within the
semiconductor substrate 210 to permit part of the electrons
generated by the light in the light receiving device 231 to move
thereto. A first type device isolation film 221 for isolating the
light receiving device 231 from the first electron collecting
device 233a and a first electron movement guide layer 251 may be
formed in the area extending from the position of the light
receiving device 231 to the position of the first electron
collecting device 233a at a specific light receiving depth of the
light receiving device 231 within the semiconductor substrate 210.
A shielding film 240 may be formed on and/or over the top of the
semiconductor substrate 210 to shield the first electron collecting
device 233a from the light 10.
[0059] In the image sensor for the semiconductor light-sensitive
device, the light receiving device 231 may directly receive the
light. However, the first electron collecting device 233a may not
directly receive the external light because it may be shielded from
the external light by the shielding film 240, and instead may
permit part of the electrons generated by the external light in the
light receiving device 231 to move thereto. Therefore, in
embodiments, the image sensor may be designed and fabricated in
such a manner that the width of the light receiving device 231 may
be relatively greater than the width of the first electron
receiving device 233a in order to maximize the light-sensing
efficiency even while minimizing the size of a unit pixel.
[0060] FIG. 8 is a cross-sectional view for explaining the
structure of an image sensor for a semiconductor light-sensitive
device, in accordance with embodiments. In comparison with the
image sensor of FIG. 7, as shown in FIG. 8, the image sensor in
accordance with embodiments may further include at least one of:
(1) A second electron collecting device 233b that may be formed at
a predetermined depth in an upper portion of the semiconductor
substrate 210 so as to be electrically isolated from the first
electron collecting device 233a. (2) A second type device isolation
film 223 for isolating the first electron collecting device 233a
and the second electron collecting device 233b adjacent to each
other. (3) A second electron movement guide layer 253 formed in the
area extending from the position of the light receiving device 231
to the position of the second electron collecting device 233b at a
light receiving depth relatively greater than the formation depth
of the first electron movement guide layer 251.
[0061] In embodiments, the width of the second type device
isolation film 123 may be relatively smaller than the width of the
first type device isolation film 221. This may he done (in
embodiments) to prevent the distance between the light receiving
device 231 and the second electron collecting device 233b from
being unnecessarily maximized so that the electrons generated in
the light receiving device 231 may properly move to the second
electron collecting device 233b.
[0062] It can be seen that the image sensor in accordance with
embodiments shown in FIG. 8 may further include the first electron
movement guide layer 251 and the second electron movement guide
layer 253, which is different to embodiments illustrated in FIG. 5.
The first electron movement guide layer 251 and the second electron
movement guide layer 253 may further facilitate the movement of
electrons from the light receiving device 231 to the first electron
collecting device 233a and the second electron collecting device
233b.
[0063] FIGS. 9A to 9C are cross-sectional views for explaining a
method for fabricating an image sensor for a semiconductor
light-sensitive device, in accordance with embodiments. FIGS. 9A to
9C illustrate a method for fabricating an image sensor for a
semiconductor light-sensitive device including the second electron
collecting device 233b, the second type device isolation film 223,
and the second electron movement guide layer 253, in accordance
with embodiments.
[0064] Referring to FIG. 9A, the first electron movement guide
layer 251 may be formed in the area extending from the position of
the light receiving device 231 to the position of the first
electron collecting device 233a at a specific light receiving depth
of the light receiving device 231, in accordance with embodiments.
The second electron movement guide layer 253 may be formed in the
area extending from the position of the light receiving device 231
to the position of the second electron collecting device 233b at a
light receiving depth relatively greater than the formation depth
of the first electron movement guide layer 251, in accordance with
embodiments. In embodiments, the first electron movement guide
layer 251 may be formed at a specific light receiving depth by a
first ion implantation process for implanting impurity ions, and
then the second electron movement guide layer 253 may be formed at
a greater light receiving depth by a second ion implantation
process for implanting impurity ions.
[0065] In embodiments, a first type device isolation film 221 and a
second type device isolation film 223, which may define active
regions, may be formed within the semiconductor substrate 210. In
embodiments, the width of the second type device isolation film 223
may be relatively smaller than the width of the first type device
isolation film 221. This may be done to prevent the distance
between the light receiving device 231 and the second electron
collecting device 233b from being unnecessarily maximized so that
the electrons generated in the light receiving device 231 may
properly move to the second electron collecting device 233b.
[0066] Referring to FIG. 9B, the light receiving device 231 may be
formed within the semiconductor substrate 210 to receive light, in
accordance with embodiments. The first electron collecting device
233a to which part of the electrons generated by light move may be
formed to be isolated by the first type device isolation film 221,
in accordance with embodiments. The second electron collecting
device 233b to which part of the electrons may move from the light
receiving device 231 may be formed to be isolated by the second
type device isolation film 223, in accordance with embodiments. In
embodiments, the light receiving device 231, the first electron
collecting device 233a, and the second electron collecting device
233b may be simultaneously formed, and the formation order may be
interchangeable even if they may be sequentially formed.
[0067] Referring to FIG. 9C, the shielding film 240 may be formed
on and/or over the top of the semiconductor substrate 210 to shield
the first type device isolation film 221, the first electron
collecting device 233a, the second type device isolation film 223,
and the second electron collecting device 233b from external light,
in accordance with embodiments. In embodiments, the shielding film
240 may be formed of a non-transmittive metal. In embodiments,
although the light receiving device 231 may directly receive light,
the first electron collecting device 233a and the second electron
collecting device 233b may not directly receive external light as
they may be shielded from the external light by the shielding film
240, but part of the electrons generated in the light receiving
device may move by the external light. In embodiments, in order to
maximize the light sensing efficiency even while minimizing the
size of a unit pixel, the image sensor may be designed and
fabricated so that the width of the light receiving device 231 may
be relatively greater than that of the first electron collecting
deice 233a and the second electron collecting device 233b.
It will be obvious and apparent to those skilled in the art that
various modifications and variation can be made in the embodiments
disclosed. Thus it is intended that the disclosed embodiments cover
the obvious and apparent modifications and variations, provided
that they are within the scope of the appended claims and their
equivalents.
* * * * *